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Potential Natural Vegetation Groups, v2000

This map is based on a terrain-matched refinement of Kuchler's Potential Natural Vegetation (PNV) map. Kuchler's PNV map was digitized for the conterminous United States, then adjusted to match terrain using a 500 meter Digital Elevation Model, 4th Code Hydrologic Unit delineations, and Ecological Subregions (Bailey's Sections). These biophysical data layers were integrated with current vegetation layers, Resource Planning Act's Forest Types and Forest Densities of the United States, and USGS EROS Data Center's Land Cover Characterization database, to develop generalized successional pathway diagrams. Expert regional panels refined the PNV map based on these successional pathways.

PNV is the "climax" vegetation that will occupy a site without disturbance or climatic change. PNV is an expression of environmental factors such as topography, soils and climate across an area. Where cover type is a classification of existing vegetation, PNV is a site classification based on climax vegetation. Because the existing cover type at any particular location and time may reflect a vegetation community anywhere along its successional pathway - from seral to climax - the cover type may be the same as the PNV.